Telephone line identification



y 1943- R. TAYLOR ETAL 2,318,267

TELEPHONE LINE IDENTIFICATION Filed Dec. 16, 1940 4 Sheets-Sheet 1 Fig. l.

v INVENTORS REGINALD TAYLOR ssoeesr/xoms BAKER ,4 TTORNEY May 4,1943.

R. TAYLOR ETAL TELEPHONE ,LINE IDENTIFICATION Filed Dec. 16, 1940 4 Sheets-Sheet 2 Fig.2.

ATTORNEY May 4, 1943. R. TAYLOR ETAL 2,318,267

TELEPHONE LINE IDENTIFICATION I I Filed Dec. 16, 1940 4 Sheets-Sheet 5 Fig.5.

INVENTORS REGINALD TAYLOR 6:0 as moms BAKER rm/WE) Patented May 4, 1943 TELEPHONE LINE IDENTIFICATION Reginald Taylor and George Thomas Baker, Liverpool, England, assignors to Associated Telephone & Telegraph Company, Chicago, 111., a

corporation of Delaware Application December 16, 1940, Serial No. 370,362 In Great Britain January 4, 1940 The present invention relates to telephone systems, and is more particularly concerned with such systems in which calling line identification equipment is provided by means of which the identity of a subscriber who has initiated a call to an operator, for instance a toll, trunk or phonogram operator, may be obtained automatically, thus rendering unnecessary the demanding and verification of the number of the calling line.

Proposals hitherto put forward for the purpose of indicating the identity of a calling subscriber to an operator have suggested visual means therefor which would be mounted on the operators position and which might take the form of a lamp display as used in the call indicator system or of electromagnetically operated step-by-step counters or other suitable equivalents. An objection to these proposals is that they involve additional mounting space on the operators positions.

The general object of the invention is to provide an improved means of advising an operator of the identity of a calling line or point and according to the invention a verbal announcement scheme is employed in which the identity of a line is first caused to be transmitted to a storage de vice which in turn causes Voice currents corresponding to the identifying characteristics of the line to be connected up successively to an operators or attendants position to cause audible sounds to be produced in correct order correspending to the identity of the line. Y

' The invention will be better understood from the following description of one method of carrying it into effect, reference being had to Figs. 1 to 4 of the accompanying drawings. These disclose an operators position, and verbal announce ment equipment common to a plurality of cord circuits at the position, only one of which cord circuits is shown in detail since the others are similar; the common equipment includes apparatus for registering an impulse code representative of the calling subscribers telephone number and for translating this into an audible announcement of the number.

Preferably a manually operated switching device is adapted to initiate the operation of the identification equipment which after storage causes an audible announcement of each digit or other identifying characteristics to be made by a telephone receiver.

In this system each operator is provided with a position circuit shown at the bottom of Fig. 4 and .a number of plug ended cord circuits with associated monitoring and speaking keys of which one is shown at the top of Fig. 4. When a speaking key is thrown the cord circuit corresponding thereto is connected to the position circuit with which all the necessary facilities such as busy test, dialling, key-sending and the like are associated.

7 Claims. (01. 179--27)' The monitory key KM and its contacts KMI, KM2 and KM3 normally serve for connecting up the transformer MTRL receiver OR over contacts ml and m2 due to operation of relay M.

For the purpose of verbal announcement of calling numbers, each operators position has-associated with it additional equipment which connects with th common leads extending between her cord circuits and her'position circuit, and leads to a known form of electrical speech reproducer, for instance of the type used in speaking clocks and the like, and employing ten speech coils designated 1-0. In these coils are induced at periodic intervals, for instance at half second intervals, the corresponding audible digits 1-0, equipment being provided whereby the operator is connected up to various speech coils in turn-in accordance with the particular calling number transmitted forward from the calling line'identification equipment at the calling exchange. Considering now a typical call from a subscriber on an exchange to a main exchange operator at a position equipped with'verbal announcement equipment, on receiving a calling signal she plugs an idle cord circuit into the calling line equipment in the usual manner and on depression of the cord circuit speaking key KSI a switching relay SK is operated from battery over resistance, lead SKL, gr3, KSI, both windings of SK, skrl to earth and switches the cord circuit through to the common position equipment at s7c3 and-sled. Relay SK in operating operates at .9702 a relay SKR and as a result an earth is extended on to the MN common at skrl, and in this instance in addition to existing relay MN being ope'rated in the position circuit, a relay HR in'the verbal announcement equipment is operated over contact grZ which in turn energises relay SP via the home contact I of the bank RI of the switch It and con tacts hrl tbl and sw l.

Theoperator now receives the subscribers request and if this is such as to require iden'tifica tion as will be the usual case at atoll, trunk'or phonogram position, she will momentarily depress the receive identification key KR! Relay SW is thereupon operated over KRII and locks via bank and wiper RI and disconnects the slugged relay SP at swl while at stud and S105 it disconnects the secondary of transformer STR in operators set from the talking leads and connects these leads to the tone commons over contacts of switches WS, XS, YS, ZS. During the slow release period of relay SP a -cycle pulse is sent back over leads l5 and [6 (Fig. 2) contacts spl and spZ, leads TA, RA, contacts s7c3 and 3704 to the incoming trunk and thence to the originat ing exchange so as to set into operation the subscribers line identification equipment provided thereat. .This equipment will preferably be of 321,783, filed March 1, 1940, by which it is possible to identify a plurality of lines simultaneously, and which transmits the identity of a calling party forward on a code pulsing basis.

For the purpose of the present invention a slightly different type of code signalling is employed, but the general principles are still the same. The code employed is of' the well-known i-unit type and necessitates the transmission of four pulses per digit, each setof four pulses being effective at the main exchange on a group of storage relays W, X, Y, Z, the storage relays for the first digit of a number being designated WA, XA, and for the second digit WIB, XB and so on.

The storage relays WAZA are operated in the following combinations in response to the first digit:

The same remarks apply to succeeding, digits except that the WBZB and WC-ZC sets of storage relays etc., are successively involved.

The equipment shown is capable of receiving up to six digits and therefore sixv sets of storage relays are provided, access to each of the twentyfour storage relays being had over a -point receiving switch R. If it was desired to cater for more than six digits a 50-point receiving switch would conveniently be used and the appropriate storage relays added.

Assuming that the calling subscribers number 4 consists of. the fuil complement of six digits, the identification equipment on determining the identity of the calling party will transmit forward to the verbal announcement equipment a train of twenty-four pulses comprising six sets of four pulses each and utilising for every pulse a 50- cycle frequency. On certain pulses a 150-cycle frequency will be transmitted in addition in order to bring about the operation of particular storage relays in each set.

The 50-cycle frequency which is transmitted during every pulse operates a suitably tuned relay PA which at contact pal completes a pulsing circuit for magnet RM to advance the receiving switch R step-by-step through its twenty-four positions, after leaving its first position the circuit for relay SW is maintained over M3 and the commoned bank contacts engaged by Wiper RI. Whenever it is desired to operate a storage relay the l50,cycle pulse is transmitted at the same time and brings about the operation of relay PB in addition to relay PA, so that earth is extended over contact pbl, wiper and bank R4 to energise the appropriate storage relay WA, XA, WB, XB, etc. The energised relays lock operated over contacts such as wal, xal, yal, eal to common lead I! to which earth is connected by M5.

In order to ensure that the R switch magnet RM, always obtains an adequate operating pulse, relay PC operates on energisation of the magnet over rm: and hr2 and thereupon looks at pol and at the same time maintains an operating circuit to the magnet over pol until the magnet interrupter contacts open when it releases and opens the magnet energising circuit.

Assuming for example that the first two digits of a subscriber's number are 38, in which case it will be necessary to operat relay YA in the A group of storage relays and relays X13 and YB in the B group of storage relays, the third, sixth and seventh pulses received will comprise both the 50-cyc1e and lSQ-cycle frequencies, so that relay PB will operate in these positions of the R switch wiper and will bring up relays YA, KB and YB.

As previously stated, the equipment caters for a maximum of six digits, but in order that the equipment may cater for mixed numbering schemes employing say 4, 5 and 6 digit numbers, automatic cut-01f facilities are provided which after a short delay release relay SW after either a 4, 5 or 6 digit number. It will be noted that the RI bank contacts I7 and 2| in addition to contact 25 which the wiper RI reaches after receipt of a 6 digit number, do not provide any circuit for relay SW, and hence if the subscriber's number consists of four or five digits only, the, R switch will stop on one of these contacts and relay SW will release after an interval governed by its slug. If the number consists of more than the number of digits which have brought the wiper to such a contact relay SW will hold operated during the transit of wiper Rl over these'contacts, since the speed of pulsing is such that the wiper is on each contact for a period less than the holding time of relay SW.

At any period after receipt of the first four pulses, i. e., the first digit of the number, the operator may pick up the subscriber's identification. She may, if preferred, proceed with the building up of the connection to the called party or alternatively she may obtain the calling subscribers number immediately by depressing the locking Identification key Kl. Relay MN in the position circuit is thereupon released at contact K12 and relay M therein is operated over K12, lead M, contact mnl by the earth extended from the cord circuit over ski-l, and as a result the operators receiver OR is connected up to the high impedance secondary winding of the monitoring transformer MTR, the primary windings of which connect up over mnZ and mn3 to leads MT and MR and hence through the armatures of switching relays WS, XS, YS and ZS to the speech coils 1-0 of the speech machine.

The operators monitoring coil in preference to the ordinary speech transformer STR has been selected for announcing the number of a calling party, since due to its high impedance it provides the least load on the speech machine, and also prevents any noise from being propagated on to the speech machine commons from the operators transmitter OT as would be the case if the ordinary operators telephone circuit wer utilised over STR. Other contacts K13 of key KI disconnect the monitoring commons MT and MR to avoid interference by the monitoring Keys on other cord circuits.

For convenience the transmitter OT is shown connected in series with a battery feed coil BFC in series with relay OR and primary of STR but this forms no part of the present invention and could be replaced by any known operators set.

Assuming now that when the key KI is depressed the first digit has been completely re-- ceived, wiper R3 will be standing on the 5th contact or on some contact beyond this and battery through resistance and contact KII is thereupon extended over wiper and bank R3 to relay IG, contact hM, first contact and wiper SI of switch S. Relay IG locks up over contacts hrd and ig2 and controls amongst other things the extension of pulses over ig3, wiper S2 to the magnet SM of the audible digit transmission wiper S2.

switch S. At contact igl a circuit is closed for relay ST from battery and resistance connected to commons M to commons I3 connected to relay ST which at stl connects up a pulsing circuit from cam contacts SMC to relay PAS. As however relay ST is common to a number of such equipments relay PAS might be already pulsing and in order that magnet SM shall not receive:

ranged in known manner that relay IG shall only operate during a time when relay PAS is de-energised and contact Pasl opens to remove;

a short circuit.

Relay IG also at contacts 1'95, ig6, igl, ig8 connects up relays WS, XS, YS, ZS to wipers S3, S4, S5, S6 respectively.

When the cam contacts SMC close relay PAS is operated and extends an earth to energis'e the magnet of the switch S over pasl, z'g3 and At the beginning of the next silent period of the tone commons, when relay PAS releases, the S switch wipers will be stepped to contact 2.

With the wipers of this switch on contact 2 certain of the relays WS to ZS are operated over wipers S3, S4, S5 and S6 in accordance 'with the A group storage relays already operated in response to the first digit received, and since in this case relay YA is assumed to be operated, relay YS will operate.

Relay YS in operating connects up the monitoring commons MT and MR over wsl and zsl, ,rsl and ysZ, 11.93 and 11.94, as 3 and ws3 to speech coil 3 and digit 3 is thereupon verbally communicated to the operator during the next on period of the tone commons.

After this period has elapsed the switch S is stepped on to position 3 which connects up to the relays WBZB, and since relays KB and YB are assumed to be operated, relays XS and YS will be operated.

During the next on period the operator will receive the second digit 8 and so on, the switch S stepping on its wipers during each silent period and operating the relays WSZS in accordance with the succeeding stored digit so that the operator will thus hear a successive series of audible digits corresponding to the callin subscriber's number.

The switch S will continue to step a number of contacts corresponding to the maximum number of digits in the area, and if the calling subscriber has less than six digits in his number certain of the later contacts will be silent, since no storage relays will be operated. When the switch has stepped through the maximum number of contacts catered for, no further circuit can be completed to its magnet, and it will remain in this position until key KI is restored and relay IG released whereupon a stepping circuit will be completed for magnet SM over wiper SI, contact 2'94, interrupter contacts sm, magnet SM to battery, when switch S will automatically rotate to the home position.

Should the operator desire to hear the number over again she may merely re-depress key KI when the above described cycle will be repeated.

The storage relays WA, etc., remain looked over their respective contacts wal, etc., and contact hr5 until the cord circuit speaking key KS is restored. The opening of contacts KS! of the cord circuit speaking key removes a short circuit across the relay GR which exists over lead sH, skr2, key KSI, lead SKL, contact yr?) and wipers R2 and ST and their contacts in parallel when in ofi-normal position and includes contact gr3 and leads SKL. '.Relay GR may now operate from the earth extended to'its upper side via the low resistance winding of relay SK in the cord circuit contact slcr2'to a battery in the operators position circuit which is connected on to its lower side via lead SKL and banks and wipers R2 and S1 in parallel. It should be mentioned that the purpose of the short circuit is to prevent slipping of the last train of impulses transmitted for setting up the connections should the operator prematurely replace the speaking key and actually both key DAKl and relay DB and its contact do not form a material part of the invention. Relay GR in operating extends an earth back over lead SH to short circuit and release the switching relay SK in the cord circuit and so remove the connection at'skS and 8M to the leads between the answering plug to the calling plug. At the same time it guards the position circuit against seizure by any other cord circuit on a position at grl, and at armature grd it connects the verbal announcement equipment supervisory lamp LP to circuit H to cause it to light while at contact gr? it releases relay HR. Relay HR in releasing releases the storage relays already operated and restores switch R to its home position over Rl, M3, M2, rm and RM; Should either switch R'or S have failed to home, relay GR will remain operated and a delayed alarm will be brought into operation.

Under normal conditions when the switches R and S reach their home position, relay GR releases and the verbal announcement equipment and .position equipment are then free for further use.

Should any fault occur in the sending in of the indentification signals, switch R will fail'to step and relay SW will remain locked. The time delay relays TA and TB then come into operation in well known manner over cam contacts S and Z, contacts sw3 and 1502 respectively. Relay TA being maintained operated over ml and sw2 until relay TB is energised and relay TB at con tact tbl releases relay SW and at contact 15122 connects lead In to flash the supervisory lamp LP on the position circuit so as to inform the operator that she must obtain the calling number direct from the subscriber and at contact tb3 to connect up a slow acting alarm circuit over commons [2.

It will thus be seen that the invention provides a very ready means by which the setting up of long distance or other calls requiring recording can be facilitated, and although it has been described in connection with the verbal announcement to an operator of the number of a calling subscriber, it may be used in other circumstances for verbally announcing the identity of a calling line or point. For example, it has further use in telephone systems for verbally announcing to an operator, maintenance ofiicer or test clerk, the identity of a faulty line on which calling conditions are simulated.

through which all such calls from a number of adjacent exchanges will be routed. In the case of multi-oflice areas where the difierent exchanges are characterised by a prefix digit or digits or by prefix letters, it could be readily arranged that the verbal announcement equipment on receiving the code signals corresponding to these prefix digits or letters, which code signals would preferably be added in the outgoing relay set at the originating exchange, would prepare for the initial announcement of the first three letters of the calling exchange instead of announcing the actual prefix digits or the digits corresponding to the prefix letters of the exchange. Although extra apparatus would be required in the announcement equipment together with extra speech coils in order to announce verbally the various alphabetical letters, the operators work in such multi-ofiice areas would be considerably simplified, as she would be directly informed of the identity of the exchange on which the calling subscriber was situated and Would be relieved of the necessity of having to translate the initial digit or digits into the corresponding exchange designation.

In the case of director areas where a three letter code prefixes the four digit subscribers numbers it will not be essential to transmit three corresponding code digits to the central exchange in view of the fact that since only a small group of exchanges out of the total in the area will be operating into each central exchange, one digit or at the most two digits could be transmitted forward to the central exchange to identify the particular exchange in the group which is calling. These digits will be translated by the verbal announcement equipment into the first three letters or like recognisable equivalent such as the actual name of the calling exchange.

We claim:

1. In a telephone or like system, a line over which two trains of impulses are transmitted concurrently, a plurality of devices, a switch operated by one of said trains of impulses to connect up each of said devices in turn, means responsive to each impulse of said other train for operating the one of said devices which is connected up by said switch at the time that impulse is received, means effective after said switch has connected up all of said devices for deter mining which of said devices are operated, and means controlled by said devices for making audible announcements of difierent digits depending upon the devices operated. v

2. In a telephone or like system, a plurality of registers, a switch operated to connect'with said registers in succession, means for operating any of said registers over said switch when said switch connects with that register, whereby said registers may be operated in a variable combination, means effective after said switch has connected with all of said registers for then testing said registers simultaneously, and means controlled by said testing means for making an audible announcement of any digit, the digit announced depending upon the combination in which said registers are found to be operated at the time tested.

3. In a telephone or like system, a plurality of devices, a switch operated to connect with said devices in succession, means for operating any of said devices over said switch when said switch connects with that device, means for testing said devices in groups, said last means effective to test all of the devices in each group at once and to test different groups successively, and means governed in accordance with the test on each group of devices for making an audible announce of any digit, the digit announced depending upon which one or more devices in the tested group are found to be operated.

4. In a telephone system, an operators position at which terminate lines over which impulse codes corresponding to difierent digits are transmitted to said position, each said code comprising current variations not within the audio frequency range, a cord circuit at said position operable to connect with any of said lines, means associated with said position and effective, when said cord circuit is connected to one of said'lines, to receive over said cord circuit such an impulse code transmitted to'said position over said line, and means controlled by said last means for translatingthe received impulse code into an audible announcement of the digit corresponding to said code.

5. In a telephone system, an operators position at which terminate lines over which impulse codes corresponding to diiierent digits are transmitted to said position, a cord circuit at said position operable to connect with any of said lines, means associated with said position and effective, when said cord circuit is connected to one of said lines, to receive over said cord circuit an impulse code transmitted to said position over said line, a device manually operated by the operator at said position after saidcode has been received, and means rendered effective by the operation of said device and controlled by said first means for translating said received code into an audible announcement of the digit corresponding to said code.

6. In a telephone system wherein a connection is extended from a calling line to an operators position and wherein the telephone number of said calling line is transmitted over said connection to the operator's position in the form of an impulse code, means at said position for receiving and storing said code, and means subsequently controlled by said last means in accordance with the stored code for translating said code into an audible announcement of said calling lines telephone number.

'7. In a telephone system wherein a connection is extended from a subscribers line to an operators position and wherein two trains of impulses thereafter are transmitted concurrently tosaid position over said connection, a plurality of devices associated with said position, a switch at said position operated by one of said trains of impulses to connect up each of said devices in turn, means responsive to each impulse of said other train for operating the one of said devices which is connected up by said switch at the time that impulse is received, means effective after said switch has connected up all of said devices for determining which of said devices are operated, and means controlled by said devices for making audible announcements of different digits depending upon the devices operated.

REGINALD TAYLOR.

GEORGE THOMAS BAKER. 

